Optical engines, such as transmitters and receivers, are typically coupled to single-mode optical fibers for the communication of data. The bandwidth-distance product for data communications systems using existing optical engines is around 2.5 Gpbs-km. Increasing the bandwidth-distance product above that value, for instance, to around 1 Tbps-km, such that the data communications systems may be implemented in large datacenter and campus networks often requires the use of signal regenerators, cascaded switches, or other relatively expensive alternatives. The use of such additional components adds to the cost and complexity of the data communications systems.
Conventional semiconductor and optoelectronic devices use Silicon on insulator (SOI); however, Germanium has been recognized as a superior material because Germanium has a very high carrier mobility and generally superior transport properties. For example, Germanium's electron mobility is two-fold larger and its hole mobility is four-fold larger relative to Silicon. However, it has been found to be difficult to implement Germanium and Silicon because they have different lattice structures, e.g., a Silicon-Germanium interface typically exhibits a lattice mismatch of about 4%. As a result, the resulting Germanium crystalline structure exhibits undesirable characteristics for many types of applications. For instance, conventional techniques for Germanium crystalline growth typically result in relatively large densities of defects.